Abstract
Objective
Recent trials show that in patients with atrial fibrillation (AF), pulmonary vein isolation performed with bipolar surgical ablation clamps using small bilateral thoracotomies is more effective than pulmonary vein isolation using standard catheter ablation. This improved efficacy comes with higher invasiveness including difficulty in execution and potentially more acute complications. Monopolar “loop” devices overcome these drawbacks but at the potential cost of decreased efficacy. Technology that has bipolar effectiveness but with improved access and safety profiles, capable of being deployed endoscopically on a beating heart, would be desirable. We evaluated an ablation system that may have all of these characteristics.
Methods
Between May 2012 and May 2013, 30 patients were treated surgically for AF using a right-sided endoscopic approach with robotic assistance. In each patient, a “box” ablation lesion set was created around all pulmonary veins with a new linear suction-applied dual-mode (monopolar and bipolar) radiofrequency (RF) ablation device that was looped around the pulmonary veins. Temperature-controlled RF was applied for 60 seconds, with a set temperature of 70°C, first in the bipolar mode and then in a separate RF ablation for 60 seconds at 70°C in the monopolar mode. Acute effectiveness of the procedure was assessed using conduction block testing and by attempting to induce sustained AF with rapid atrial pacing. The left atrial appendage (LAA) was occluded in all patients with multiple ENDOLOOP snares using a left video-assisted thoracoscopic surgery approach under transesophageal echocardiography guidance, after which the tip of the LAA was incised to empty the LAA of blood. All patients were seen clinically at 30, 90, and 180 days with routine electrocardiography monitoring: at 6 months, 24-hour Holter monitoring was performed.
Results
Acute conduction block was achieved in 93% the of patients, and sustained AF could not be induced by rapid atrial pacing after the surgical ablation procedure in 90% of the patients. At 3- and 6-month follow-up, 88% and 81% of the patients, respectively, were in sinus rhythm. Of 16 the patients seen at 12-month follow-up, 14 (88%) were in sinus rhythm with 44% still on antiarrhythmic medications.
Conclusions
The newly introduced bipolar/monopolar RF ablation device can be easily positioned using a right endoscopic approach. Robotic assistance enables effective fat removal for accurate and easy placement of the device around the pulmonary veins. With the use of this approach, the device is safe and effective in electrically isolating the pulmonary veins.